The regulation of water and sediment by use of cascade reservoir group is one of the most effective ways to solve the serious situation of sediment deposition in the upper reaches of Yellow River. Based on the long series data of water and sediment from 1956 to 2010, this paper analyzed the law of water and sediment,and regulation time in the desert starch reaches.Longyangxia and Liujiaxia cascade reservoirs are chosen as the regulation mean.Under the mode of water resources determining power generation, this paper established the joint operation model of cascade reservoirs in the upper reaches of Yellow River.Then three scenarios are set and the results showed that (1) the maximum water demand for 14 and 30 days of water and sediment regulation in the desert starch reaches are 3.2 billion m3and 6.7 billion m3 respectively; (2) the paper gave the potential of water and sediment regulation by cascade reservoir group in quantity, the cycles of one water and sediment regulation for 14 is two years and that for 30 days is three years. The research has important guiding significance and application value for the regulation of water and sediment and the optimization operation of cascade reservoir group in the desert starch section of upper reaches of Yellow river.